1. Field of the Invention
The present invention relates generally to an apparatus and method for measuring the volume of urine in a bladder using ultrasound signals, and more particularly, to an apparatus and a method which can accurately measure the volume of urine in the bladder using ultrasound signals regardless of the detection location on which a transducer is placed.
2. Description of the Related Art
Generally, an ultrasonic system is a system that emits ultrasonic signals to an object to be examined using the piezoelectric effect of a transducer, receives the ultrasonic signals reflected from the discontinuous planes of the object, converts the received ultrasonic signals into electrical signals, and outputs the electrical signals to a predetermined display device, thus enabling examination of the internal states of the object. Such an ultrasonic system is widely used for medical diagnosis equipment, non-destructive testing equipment or underwater detection equipment.
When diagnosing bladder abnormalities or urinary difficulty, measuring the volume of urine in the bladder is an essential procedure. Furthermore, prior to urination using a catheter, the volume of urine in the bladder should be measured to account for urine that may be retained after the operation. In addition, in urination training, the amount of urine in a bladder should be measured as a guideline.
Various types of ultrasonic scanning equipment may be used to measure the volume of urine in a bladder. In this case, two methods are used. A first method calculates the amount of urine from ultrasonic images for a perpendicular plane and a horizontal plane, which are obtained using typical ultrasonic scanning equipment. However, although many algorithms has been proposed and used for the first method, the first method is problematic in that it not only has a considerable error rate but also exhibits different results for different operators. A second method uses dedicated ultrasonic equipment for measuring the volume of urine in the bladder. U.S. Pat. No. 4,926,871 discloses dedicated ultrasonic equipment. However, the dedicated ultrasonic equipment based on the second method has a disadvantage in that it also calculates the amount of urine chiefly using two ultrasonic images of a bladder, and in that a operator must find an ultrasound scan plane having the area of the bladder with the greatest size and select it in order to calculate of the amount of urine.
FIG. 6 is a diagram showing the areas of a bladder in the ultrasound scan planes when the transducer is placed on the center of the bladder. FIG. 7 is a diagram showing the areas of a bladder in the ultrasound scan planes when the transducer is placed on the position which is moved from the center of the bladder. Referring to FIGS. 6 and 7, the cross-section areas of the bladder according to B-B′ are different each other. The volume of bladder calculated using the areas of bladder can be varied according to the position where the transducer is placed.
Accordingly, the present applicant proposes a method of accurately calculating the volume of urine in a bladder while minimizing operator interference.